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I know ive seen teams with aluminum restrictors but i can't machine one with any type of presicion. Ive done one out of machinable wax already, but when i switched to aluminum i got a horrible surface finish. The boring bar seems to be vibrating quite a bit but i cant shorten the length of it at all or i won't be able to reach the throat of the restrictor with it. Anyone have any suggestions or tricks for maching the restrictor?
I know ive seen teams with aluminum restrictors but i can't machine one with any type of presicion. Ive done one out of machinable wax already, but when i switched to aluminum i got a horrible surface finish. The boring bar seems to be vibrating quite a bit but i cant shorten the length of it at all or i won't be able to reach the throat of the restrictor with it. Anyone have any suggestions or tricks for maching the restrictor?
get someone else to do it?
We have run aluminum ones in the past...from what I have heard, it took forever to make, very small cuts to keep deflection of the boring bar to a minimum.
You would almost have to have it cnc'd unless you dont care about the profile and have a few days to sit at a lathe.
Mike Duwe
UWP Alumni
Former Drivetrain Leader and Team Captain
Well i am cncing it, but i still have the problem with vibration and deflection in the boring bar. We have made aluminum ones in the past but they were all two piece with a flange so the boring bar length and deflection wasnt much of an issue. I am trying to make this one one piece.
ours were 1 piece but I know they had to make a few sets to get it as close to the desired restrictor dia at the throat.
Mike Duwe
UWP Alumni
Former Drivetrain Leader and Team Captain
Make a reinforced boring bar. This cut is about 6.5 inches deep with no chatter at all. The boring bar only has about .030" clearance throughout the cut - you need to model up the restrictor and the boring bar to get it as stiff as possible. Adding some rubber o-rings helps out as well, and of course get your speeds and feeds right.
Billy Wight
University of California, San Diego - Formula SAE 2004-2006
Try using a carbide boring bar. Use the absolute thickest one you can, make sure your insert is sharp, etc. Run light DOCs, try running really low RPMs (200-300).
Colorado FSAE | '05 - '07
Goodyear Tire & Rubber | '07 - '11
NASCAR Engineer | '11 - ??
It might sound half-assed, but get close with tooling and then use sand paper on the lathe to get your last few thou. Surface finish comes out great and as long as you keep checking your throat you can get very close to size.
'engine and turbo guy'
Cornell 02-03
That reinforced bar looks like it would work pretty well. I assume you made the taper before going boring all the way through. I was running rubber bands on it to try to dampen some of the vibration out but it didnt help much. Did you drill holes through the boring bar then to mount that sleeve? I'll have to talk that one through with the shop boss before i try that one.
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